1. Field of the Invention
The present invention relates to an electrophoresis display device, and more particularly, to an electrophoresis display device and a driving method thereof, which decrease a leakage current during an idle period and thus reduce consumption power.
2. Discussion of the Related Art
Electrophoresis display devices denote devices that display an image with electrophoresis in which colored charged particles move by an electric field given from the outside. Herein, electrophoresis denotes that when an electric field is applied to e-ink where charged particles are dispersed into liquid, the charged particles moves inside the liquid by Coulomb force.
When materials with electric charges are placed in an electric field, the materials perform unique movement according to the sizes and shapes of molecules and electric charges. Materials being separated by a moving difference between materials are called electrophoresis.
Electrophoresis display devices using electrophoresis have bistability, and thus can maintain a displayed image for a long time even when an applied voltage is removed. That is, since electrophoresis display devices maintain a constant screen for a long time even when a voltage is not continuously applied thereto, the electrophoresis display devices are display devices suitable for an e-book field that does not require the quick change of a screen.
Moreover, electrophoresis display devices are not dependent on a viewing angle unlike liquid crystal displays (LCDs), and moreover, provide an image comfortable for eyes similarly to papers. Furthermore, electrophoresis display devices have flexibility, low power consumption, and eco like. Accordingly, the demand of electrophoresis display devices is increasing.
FIG. 1 is a diagram illustrating an electrophoresis display device of the related art. FIG. 2 is a diagram illustrating a driving method of an electrophoresis display device of the related art.
Referring to FIGS. 1 and 2, the related art electrophoresis display device (EPD) includes a plurality of gate lines (scan lines) 10, a plurality of data lines 20 that intersect the gate lines 10, a plurality of electrostatic discharge (ESD) circuits 60, an electrophoresis film (not shown), and a plurality of driving circuits (not shown). Each of the driving circuits includes a data driving circuit, a gate driving circuit, and a controller.
The data driving circuit generates data voltages corresponding to image data and respectively supplies the data voltages to the data lines 20. Herein, each of the data voltages is generated as a positive voltage or a negative voltage according to the grayscale level of corresponding image data.
The gate driving circuit generates a gate pulse (scan pulse) that swings between a gate high voltage (VGH) and a gate low voltage (VGL), and sequentially supplies the gate pulse to the gate lines 10.
The controller controls the data driving circuit and the gate driving circuit.
An LCD supplies image data to a liquid crystal panel thereof in units of a frame to display an image, causing large power consumption. However, an EPD supplies image data to a display panel thereof to convert an image and then maintains display, without requiring separate power.
Such an EPD, as shown in FIG. 2, is driven in three stages such as a power-on period, an update period, and an idle period, thereby displaying an image. Also, in the EPD, a screen conversion is performed from a previous screen to a screen next thereto.
The power-on period is a period where an EPD is being turned on for displaying an image.
The update period is a period where the image data of a display panel are updated for a conversion from a previous screen to a screen next thereto.
The idle period is a period that stabilizes image data supplied to the display panel, and specifically is a system stabilization period for maintaining the display of an image for a certain time.
For a conversion from a previous screen to a screen next thereto, the EPD supplies waveforms to a plurality of pixels in the display panel, respectively. Herein, in the EPD, a screen conversion is not fast due to the characteristic of bistability, and thus, by supplying a waveform that is the sequence of image data for a screen conversion, a conversion is performed from a previous screen to a screen next thereto.
In this case, new data are respectively written in the pixels through a data update operation that is performed for about 1 second, and then current data are maintained until being updated to next data.
In this way, the EPD stabilizes an image by maintaining the idle period for a certain time after the update of the image data, and even when the idle period is ended and then power is not supplied to the display panel, the EPD maintains the display of the image for a long time.
In such an EPD, a plurality of ESD circuits 60 are applied to respective start portions of the data lines 20, for preventing damage due to static electricity that is generated in the display panel. Also, a plurality of ESD circuits 60 are applied to respective start portions of the gate lines 10, and a plurality of ESD circuits 60 are applied to respective end portions of the gate lines 10.
When external static electricity is applied to the display panel, the ESD circuits 60 discharge the external static electricity. The ESD circuits 60 are provided into the display panel, for protecting a plurality of active areas of the display panel from the external static electricity.
One side of each of the ESD circuits 60 is connected to a corresponding gate line 10 or a corresponding data line 20, and the other side of each ESD circuit 60 is connected to a ground (GND) 40. The gate lines 10 and the data lines 20 are connected to the ground 40 through the respective ESD circuits 60.
In the EPD, after the power-on period and the update period, a stabilization voltage of −20[V] is supplied to the gate lines 10 for a certain time for stabilization of an image during the idle period.
At this point, as illustrated in FIG. 1, a current path is formed by an electric potential difference between a ground voltage and a stabilization voltage of −20[V] that are supplied to each of the gate lines 10. When a current path is formed on each of the gate lines 10 and data lines 20 connected to the ground GND, a leakage current 70 is generated.
A source voltage VCC is powered off during the idle period, and thus, consumption power is required to be reduced. On the contrary, consumption power is increased by the leakage current 70 due to the stabilization voltage of −20[V] that is supplied to the gate lines 10 for stabilization of an image during the idle period.